#instrumentation

Type-K thermocouple temperature/voltage conversion as an API, computed locally and deterministically from the official NIST ITS-90 reference functions. The voltage endpoint converts a junction temperature in °C to the thermo-electromotive force in millivolts using the NIST type-K direct polynomial (with its Gaussian correction term above 0 °C), and performs cold-junction compensation by subtracting the reference-junction EMF, so a hot junction at 200 °C against a 25 °C terminal block gives the EMF your meter actually reads; a type-K junction produces 4.096 mV at 100 °C and 41.276 mV at 1000 °C against a 0 °C reference. The temperature endpoint does the inverse: it takes the measured EMF in millivolts and the reference-junction temperature, refers the reading back to 0 °C by adding the cold-junction EMF, and returns the hot-junction temperature in °C and K — obtained by numerically inverting the same monotonic forward polynomial, so it is exactly consistent with the forward conversion. Type K (chromel–alumel) covers −270 to 1372 °C. Everything is computed locally and deterministically, so it is instant and private. Ideal for industrial-automation, process-control, data-acquisition, IoT-sensor, furnace and lab-instrument app developers, sensor-linearization and cold-junction-compensation tools, and embedded firmware. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 2 endpoints. This is the type-K thermocouple; for resistance-temperature detectors use an RTD/PT100 API.

api.oanor.com/thermocouple-api

Load-cell (weighing-transducer) maths as an API, computed locally and deterministically. The output endpoint computes the bridge output voltage a strain-gauge load cell produces under a given load, Vout = (load/capacity)·sensitivity·excitation, where the full-scale output FSO = sensitivity(mV/V)·excitation(V) is reached at the rated capacity — it returns the output in millivolts, the equivalent mV/V at that load and the capacity utilization, and flags overload. The load endpoint inverts this to recover the applied load from a measured bridge output, load = (Vout/FSO)·capacity. The array endpoint sizes a multi-cell weighing platform: from the number of identical cells, the per-cell capacity and the live and dead (tare) load it returns the evenly distributed per-cell load, its output and utilization and the total system capacity, so cells can be chosen to stay under capacity in the worst case. Sensitivity is in mV/V, excitation in volts (default 10), output in millivolts; load and capacity share any consistent unit. Everything is computed locally and deterministically, so it is instant and private. Ideal for industrial-weighing, scale, force-measurement, silo and process-control app developers, load-cell sizing and calibration tools, and instrumentation education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is load-cell transducer output; for the underlying Wheatstone-bridge and strain maths use a Wheatstone-bridge API.

api.oanor.com/loadcell-api

Wheatstone-bridge and strain-gauge maths as an API, computed locally and deterministically. The bridge endpoint takes the four arm resistances R1–R4 and an excitation voltage and returns the bridge output voltage between the two midpoints, Vout = Vin·(R2/(R1+R2) − R4/(R3+R4)), in volts and millivolts, the voltage at each midpoint, and whether the bridge is balanced (Vout = 0 when R1·R4 = R2·R3). The balance endpoint inverts it: give any three arms and it solves the fourth resistance that balances the bridge, the classic way a Wheatstone bridge measures an unknown resistance. The strain endpoint models a strain-gauge bridge — quarter, half or full — and converts in both directions between mechanical strain and electrical output: from a gauge factor and a strain (given directly, as microstrain or as a relative resistance change ΔR/R = GF·ε) it returns the output ratio and voltage Vout/Vin = (k/4)·GF·ε where k is the number of active arms, and from an output voltage and excitation it returns the strain and microstrain. Everything is computed locally and deterministically, so it is instant and private. Ideal for instrumentation and sensor tools, load-cell, pressure-sensor and RTD measurement design, strain-gauge and data-acquisition apps, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is bridge and strain-gauge measurement; for Ohm's law, voltage dividers and series/parallel resistor combinations use an Ohm's-law API.

api.oanor.com/wheatstone-api